Method of using a dedicated internal shunt and stent for the inferior vena cava

ABSTRACT

Disclosed is a method of diverting blood from the adult retro hepatic Inferior Vena Cava (IVC) and the shunting of renal and infra renal IVC blood to the right atrium when desired during surgery on the liver, its vessels, or the retro hepatic IVC. The device has a distal component of critical length for the adult supra renal IVC. It is symmetrical on its mid horizontal axis permitting similar utility whether venous access was above or below the liver. It is a hollow plastic tube with two openings, one at each end of the tube, which has four intervening completely encircling balloons and is continuous with a proximal component which serves to manipulate the distal component within the venous system and to remotely inflate the balloons. Once introduced via right atriotomy or venotomy the distal component would be advanced and seated in the right atrium and supra renal IVC at which time inflation of the balloon immediately below the shunt opening in the right atrium would provide for easy digital sensation within the pericardium and identification of the exact site below this balloon for occlusion by ligature the intra pericardial IVC around the shunt. This would prevent reflux of blood from the heart into the retro hepatic IVC and fix the position of the balloon immediately above the lower opening above the renal veins which when inflated would occlude the supra renal IVC and instantly cause bypass of the retro hepatic IVC and shunt renal and infra renal IVC blood to the heart.

BACKGROUND

The Inferior Vena Cava (IVC) is the largest vein in the body returningthe majority of the venous return to the heart. The mean diameter hasbeen reported to be 20 m.m. with a range from 13 to 30 m.m. with astandard deviation of 3 m.m.--see Prince, M R et al. in Radiology 1983,December: 149 (3) 687-9.

The (1) Retrohepatic vena cava, (2) Vena cava between the Right atriumand the Right renal vein, (3) The Supra hepatic vena cava, have beenmeasured by Rodrigues A. J. Junior et al., Gegerbaurs Morphol. Jahrb1987, 133 (4); 665-72. and reported respectively to be: (1) 78.34 m.m.,(2) 135. 16 m.m. and (3) 19.34 m.m.

Additionally Dr. Hee Lee at the District of Columbia General Hospital(Table I) has measured the IVC in the adult men and women utilizing theComputerized Tomogram and found the average length of the Vena Cava fromthe Right atrium to the left renal vein to be 134.2 m.m. and 124.4 m.m.in males and females respectively; and 132.2 m.m. and 123.6 m.m. inmales and females respectively from the Right atrium and the right renalvein.

The IVC is often injured in penetrating trauma to the abdomen. Mortalityis especially high-in the order of 90% when the retro hepatic Vena Cavais involved primarily for the following reasons:

1. Massive hemorrhage often results from disruption of the vena cava orattempts to expose the injured vessel in this difficult to access arealying posterior to the liver. 2. Acute interruption of the IVC byclamping the IVC above and below the liver may produce a nonperfusedretrohepatic segment but severely reduces the venous return to the heartwith the consequence of inadequate cardiac output and venous congestionand metabolic disturbances in the abdominal viscera and the lowerextremities that often result in the death of the patient.

In an attempt to avert the disastrous consequences of hemorrhage and theacute interruption of venous return consequent to IVC interruptiondescribed above, surgeons have historically created an internal venacava shunt mainly by one of two techniques: In the first technique, achest tube has been placed into the IVC through the right heart afterwhich the IVC would be encircled above and below the liver and tied downto the internal chest tube thereby creating an avascular segment in thearea of injury and an internal shunt allowing blood to return to theheart through an opening in the chest tube customized to lie within theright atrium. This technique is often unsuccessful as encircling thevena cava below the liver can be difficult and can also result ininadvertent injury to other vessels with consequent bleeding fromadditional sites.

In a second technique, surgeons have employed an endotracheal tube toinsert into the IVC similarly through the right atrium, followed byligation of the intrapericardial IVC around the endotracheal tube afterwhich the balloon of the endotracheal tube would be blown up in thesuprarenal IVC forcing the blood to shunt into the lower opening of thetube and exit through an opening customized to lie in the atrial portionof the tube. In this manner the cerclage of the vena cava below theliver with its inherent potential problems would be avoided.

In the two techniques above, one has to make a judgment each time howfar to insert the tube, where to customize the atrial opening and whereto place the inferior ligature or inflate the balloon with respect tothe renal veins and where to apply the proximal ligature with respect tothe proximal customized opening in the tube to permit venous return tothe heart.

Given the above anatomic, physiologic and technical considerations, animproved shunt for the retrohepatic IVC is hereby proposed that would:

1.) Be based on the known anatomic dimensions of the adult suprarenalIVC.

2.) Eliminate the need for customization of devices not originallyintended for the shunting of blood or for use in this location.

3.) Provide a method for the easy and accurate identification of thesite within the pericardium for the fixation of the device within thevenous system which would also occlude the IVC above the retrohepaticIVC thereby preventing reflux of blood from the heart; and also obligatethe caudal IVC occlusion balloon to position below the retrohepatic IVCsegment; which when inflated would provide for bypass of theretrohepatic IVC and an internal shunt of blood from the renal veins andthe suprarenal IVC to return to the heart.

This dedicated IVC shunt and stent, hereafter referred to as theAnderson Shunt, is depicted in FIGS. 1, 2, 3, 4, 1C and 2C, and isdescribed in the following specifications and descriptions:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a full longitudinal cross sectional view of the shunt forinsertion into the vena cava through a right atriotomy showing theballoons in an inflated posture. These balloons when deflated wouldcollapse around the shunt.

FIG. 2 depicts a narrower variation of the shunt of FIG. 1 modified indesign to include a guide wire for optional Seldinger type access of thevenous system either above or below the liver.

FIG. 3 depicts the shunt in FIG. 2 in an attitude of infrahepaticinsertion.

FIG. 4 is a figurative drawing of the device functionally seated in thevenous system showing

(1) The shunting of blood from the renal veins and infrarenal IVCentering the caudal opening of the shunt.

(2) The intrapericardial ligation of the suprahepatic IVC around theshunt at the atriocaval junction preventing reflux of blood from theheart into the retrohepatic IVC also achieving fixation of the devicewithin the venous system.

(3) Suprarenal occlusion of the IVC around the shunt above the caudalopening.

(4) The isolated retrohepatic vena cava optimized for surgery.

(5) The inflated intraatrial balloon which defines the exact site forligation and device fixation described in (2) and

(6) The orfice in the shunt above the atrial balloon which provides forvenous return from the shunt to the heart.

FIG. 5 is a figurative drawing of the device functionally seated in thevenous system. FIG. 5 is applied in the same manner as FIG. 4 exceptthat FIG. 5 is inserted into the venous system from a venous accessbelow the renal veins.

DETAILED DESCRIPTION OF THE INVENTION

The invention is depicted in FIGS. 1, 1C, 2, 2C, 3, and 4 in theappended drawings.

FIG. 1 is a longitudinal cross sectional detail of the device on a 1:1scale.

FIG. 1C is a horizontal cross sectional detail of the device above itsdistal portion, which is further described below on a 2:1 scale.

The entire device is a flexible plastic tube approximating 50centimeters (cm) long and 13 millimeters (m.m.) wide. The internaldiameter of the tube is 10 m.m. with a wall thickness of 3 m.m.

The device consists of a distal portion of critical dimensions and isdesigned for complete embodiment within the adult right atrium andsuprarenal IVC and is 160 m.m. long.

There are two 10 m.m. diameter orfices in the device on either end ofthis distal portion to allow for blood to enter the shunt from the IVC,traverse the shunt and exit the shunt in the right atrium. These orficesare labeled 1.

Four inflatable balloons encircle this distal portion of the shuntbetween these two orfices and are labeled 2, 3, 4, and 5. Each balloonwould occupy a 20 m.m. length of the tube and would be able to beinflated up to a 35 m.m. diameter and be sufficient to occlude the IVCwith a known mean diameter of 20 m.m. Balloons 2 and 5 are essential tothe operations of the shunt. Inflation or deflation of the interveningballoons lend flexibility to the shunt and may or may not be used in itsoperation depending on the nature of injury to the retrohepatic venacava.

Balloon labeled 2, when sufficiently inflated within the right atriumprovides for digital sensation within the pericardium of the appropriatepoint for fixation of the device within the venous system by ligation ofthe intrapericardial IVC around the shunt in the venous systemimmediately caudal to balloon 2. When so introduced, sensed and fixed,the cephalad 30 m.m. of this distal portion of the tube would lie withinthe right atrium with the remaining 130 m.m. of the distal portion ofthe device positioned in the suprarenal IVC cephalad to the rental veinorfices.

Balloon #5 occupies a 20 m.m. segment of the tube between 20 to 40 m.m.from the caudal tip of the distal segment. It sits immediately cephaladto the caudal orfice of the shunt and when inflated sufficiently, itserves to occlude the suprarenal IVC safely cephalad to the renal veinsorfices by a distance of approximately 25 m.m. The length of tubebetween balloons 2 and 5 is 90 m.m. and would approximate the difficultto access retrohepatic IVC. Following intrapericardial ligation of theIVC around the shunt and suprarenal occlusion of the IVC as describedabove, the desired bypass of the retrohepatic IVC and the return ofblood from the renal veins and infrarenal IVC to the heart would havebeen simply and expeditiously achieved.

The proximal portion of the device is continuous with the distal portiondetailed above and is intended for only partial embodiment within thevenous system. It serves to carry 4 tubular conduits of variable lengthsin the wall of the device labeled 12 that connect balloons labeled 2-5with respective inflation ports labeled 2'-5' located in the mostproximal 5 cm. Of the device labeled 6 such that port 2' would connectto balloon 2, port 3' to balloon 3 and so on. This proximal portion alsoprovides a means to manipulate the distal portion of the device withinthe venous system.

The ports would be Laur lock in design and the inflation fluid would benormal saline. The device described in FIGS. 1 and 1C is designed forintroduction into the venous system by way of a right atriotomy.

FIG. 2 is essentially the same device in FIG. 1 having the samelongitudinal dimensions and all the elements and details of FIG. 1 withthe following differences.

1.) The tube has a smaller diameter. Its external diameter would be 10m.m. while its internal diameter would be 7 m.m.

2.) The orfices labeled 1 in FIG. 2 would have a 7 m.m. diameter, thesame as the diameter of this smaller tube.

3.) There would be an additional tubular conduit traversing the lengthof the device for accommodating a flexible guide wire over which thetube could be passed according to the Seldinger technique.

FIG. 2C is a 2:1 horizontal cross sectional detail of the device in FIG.2 taken just proximal to the critical distal portion showing itsnarrower diameter and an additional conduit for the accommodation of aguide wire.

The device described in FIG. 2 and FIG. 2C is designed for introductioninto the venous system by way of a right atriotomy as is the devicedepicted in FIG. 1, but because of its smaller size, it may be suitablefor introduction into the venous system above or below the liver by wayof a right internal jugular vein cutdown or a right iliac vein or aright long saphrenous vein cutdown.

FIG. 3 is the same device in FIG. 2 in an attitude of infrahepaticinsertion. FIG. 4 is a graphical depiction of the device functionallyseated in the venous system with the complete embodiment of the distalsegment of the device within the right atrium labeled 8, and thesuprarenal IVC labeled 9, showing closure of the right atriotomy sitewith a prolene suture -11' around the proximal portion of the device;closure of the intrapericardial IVC around the shunt below the artialballoon with umbilical tape-11; and, an inflated suprarenal IVCocclusion balloon. Two arrows depict the entrance of blood into theorfice above the renal veins and the exit of blood into the rightatrium. The two intervening balloons are shown partially inflated. Notethe renal veins -10, the diaphragm -13 and the pericardium -14.

As depicted in FIGS. 4 and 5 the retrohepatic IVC would be isolated,bypassed and in an optimal condition for surgery. A Legend for thededicated IVC shunt (Anderson Shunt) is described in Table II.

Indications for Use

The use of the shunt is projected to facilitate the control ofhemorrhage in the following instances:

1.) When the hepatic veins or the retrohepatic IVC is suspected to havebeen injured.

2.) When significant bleeding is anticipated or realized during electiveor emergent resection of the liver for tumors or for trauma.

Technique for Supradiaphramatic Insertion of the Device

The device depicted in FIG. 1 and its "percutaneous" modification whichis smaller and depicted in FIG. 2 are preferably inserted in the venoussystem via a right atriotomy.

The smaller device may additionally be inserted into the venous systemby way of an internal jugular vein cutdown. With the exception of thesite of access the technique of insertion is the same as when the venousaccess site was the right atrium. The preferred right atriotomy accessand insertion of the device is detailed below.

(1) The abdominal midline incision used for exploratory laparotomy wouldbe extended upwards into the sternum.

(2) The pericardium would be opened and the intrapericardial IVC wouldbe encircled with umbilical tape.

(3) The right atrial appendage would be used to access the IVC throughan atriotomy encircled by a purse string suture of prolene.

(4) The device filled with normal saline would be inserted through theatriotomy and advanced through the atrium into the IVC to a distancejust beyond the atrial shunt opening--numbered -1- in the appendeddrawing. The atrial balloon labeled -2- would be inflated with justenough saline, injected through port 2', to be sensed by the fingers onthe intrapericardial IVC within the open pericardium.

(5) At this point there would be no further advance of the device, andthe previously placed umbilical tape -11, in FIG. 4 would be tightenedto collapse the intra-pericardial vena cava around the device therebypreventing blood from passing into the retrohepatic vena cava from theright atrium and also fixing the correct length of the shunt in thesuprarenal IVC.

(6) At this time inflation of the lowermost balloon -5 would be done byinjection of saline through port 5' thereby achieving occlusion of thesuprarenal IVC.

Following completion of steps 1-6, the retrohepatic IVC would beisolated and blood from the kidneys and the infrarenal IVC would enterthe shunty seated above the renal veins, bypass the retrohepatic IVC andreturn to the heart by way of the atrial orfice of the device. N. B. Theintervening balloons 3 and 4 could be inflated optionally through ports3' and 4' yielding further flexibility if such was desired depending onthe nature of the injury.

Technique for Infradiaphragmatic Insertion of the Device

There may be occasions--anatomic or technical when introduction of theshunt via a venous access point below the diaphragm and liver ispreferred. In such instances the smaller modification of the shunt maybe applicable for insertion via a right external iliac vein cutdown, orvia a right long saphrenous vein cutdown.

The attitude of the tube in such insertion is depicted in FIG. 3 inwhich case the technique of insertion would be as follows:

(1) The midline abdominal incision used for exploratory laparotomy wouldbe extended upwards into the sternum.

(2) The pericardium would be opened and the intrapericardial IVC wouldbe encircled with umbilical tape.

(3) The right iliac vein or right long saphrenous vein would be isolatedand controlled proximal and distal to the intended venotomy site.

(4) The venotomy would be affected and the saline filled device would beinserted into the venous system with or without use of the guide wireand the Seldinger technique.

(5) The device would then be advanced into the IVC and right atriumwhere the atrial balloon--now balloon 5--would be inflated and retractedenough that the balloon could be sensed digitally by fingers on theintraperdicardial IVC.

(6) At this point approximating the atrio-caval junction, the previouslyplaced umbilical tape encircling the intrapericardial IVC would betightened around the shunt immediately caudal to the atrial balloon ofthe device within the venous system thereby preventing blood fromreflexing into the retrohepatic IVC from the right atrium, as well asfixation of the correct length of IVC.

(7) At this time, inflation of the suprarenal IVC occlusion balloon--nowballoon 2--with saline, would achieve the aims of the shunt namely (1)occlusion of the IVC above the renal veins, (2) diversion of blood fromthe renal veins and the infrarenal IVC through the caudal opening in thedevice into the shunt and exit of blood through the atrial opening ofthe shunt to the heart and (3) Isolation and bypass of the retrohepaticIVC thereby producing conditions anatomically and physiologicallysuitable for surgery. This is figuratively represented in FIG. 5.

Technique of Removal

Following repair of the vena cava, and completion of the operation, theballoons can be deflated by the complete withdrawal of saline throughthe ports -2'- through -5'- and extraction of the shunt through theatriotomy or venotomy, after which the atriotomy or venotomy is closedby a using a standard technique.

SUMMARY

A device and method of fixation of the device has been proposed forachieving the bypass of venous blood away from the retrohepatic IVC andthe shunting of blood from the renal veins and the infrarenal IVCthrough the internal IVC shunt to the heart thereby achieving optimalconditions for surgery in this difficult to access location.

The unique features of the shunt include the following:

1.) Its dimensions are based on the relatively constant known anatomy ofthe suprarenal IVC and is dedicated to the shunting of blood in thisdifficult to access retrohepatic segment of the IVC.

2.) It provides a mechanism for the digital sensing of the exact pointfor fixation of the device at the atriocaval junction within thepericardium which obligates simultaneously (1) the atrial opening of thedevice to seat within the right atrium, (2) the caudal IVC occlusionballoon to position below the retrohepatic IVC and above the renal veinorfices, (3) The caudal opening of the shunt to admit blood from therenal veins and the infrarenal IVC following the saline inflation of theIVC occlusion balloon around the shunt immediately cephalad to saidopening.

This dimensionally correct device and method of fixation eliminates theneed for the customization of devices not originally designed for use inthe vena cava.

It is anticipated that the proposed device for which a patent is herebyapplied will enormously simplify and expedite retrohepatic IVC shuntingand can be expected to reduce the horrendous mortality attendant tohemorrhage from injuries in this location, under military and civilianconditions.

Given the benefits to be realized, a speedy and favorable deliberationis implored.

                  TABLE I                                                         ______________________________________                                        Measurements by    RA-RRV     RA - LRV                                        Computerized Tomography                                                                          in m.m.    in m.m.                                         Adult Men   (27)       132.2      134.2                                       Adult Wonen (23)       123.2      124.2                                       ______________________________________                                         RA = Right Atrium                                                             RRV = Right Renal Vein                                                        LRV = Left Renal Vein                                                         m.m. = Millimeters                                                       

                  TABLE II                                                        ______________________________________                                        LEGEND FOR IVC SHUNT (ANDERSON)                                               ______________________________________                                        FIG. 1 -                                                                              Shunt (1:1).                                                          FIG. 1C -                                                                             Cross Section (2:1).                                                  FIG. 2 -                                                                              Percutaneous Shunt (1:1).                                             FIG. 2C -                                                                             Cross Section (2:1).                                                  FIG. 3 -                                                                              Percutaneous Shunt in caudal insertion.                               FIG. 4 -                                                                              Shunt in IVC.                                                         1 -     Openings in the Shunt.                                                2 -     Proximal shunt balloon.                                               3 and 4 -                                                                             IVC balloons.                                                         5 -     Distal shunt balloons.                                                6 -     Proximal end of shunt with inflation ports 2', 3', 4' and 5'                  corresponding to balloons 2-5.                                        7 -     Guide wire.                                                           8 -     Right Atrium.                                                         9 -     IVC.                                                                  10 -    Renal Vein Orfice.                                                    11 -    Ligature around intra pericardial IVC.                                11'-    Ligature around right atrial shunt insertion site.                    12 -    tube in wall of shunt for saline inflation and guide wire.            13 -    Diaphragm.                                                            14 -    Pericardium.                                                          ______________________________________                                    

We claim:
 1. A pericardial method of inserting a by pass shunt into theatrio-venous system through the right atrium of the heart to ensure acontinuous flow of blood through said atrio-venous system during surgeryon the retro hepatic vena cava, the liver and blood vessels by occludingthe flow of blood into said retro hepatic vena cava and diverting bloodfrom the renal veins and the inferior vena cava through said by passshunt into the right atrium comprising the steps of:providing a closedend flexible by pass shunt having a pair of openings, one of which isfor the right atrium, the atrial opening and the other for the inferiorvena cava, the vena cava opening, said pair of openings are connected toeach other by a central conduit of said shunt so that blood can enterinto said shunt through said vena caval opening and exit through saidatrial opening and including at least two fluid conduit ducts within thewall of said shunt which are connected to external ports in the proximalend of the shunt for introducing and withdrawing fluids to at least twoexpandable and collapsible balloons which encircle said flexible shuntexternally and are connected to said external ports and wherein saidshunt is symmetrical on its mid-horizontal axis; performing an atriotomyof the right atrium of the heart to insert and seat said shunt into afixed position proximally within the right atrium and distally withinthe retro hepatic vena cava; ligating the wall of the heart at theentrance point of said shunt into said right atrium of the heart andpositioning said shunt in a fixed position within said right atrium andsaid retro hepatic vena cava so that one of said balloons encirclingsaid shunt rests in said right atrium and the other is in the inferiorvena cava; partially inflating said balloon in said right atrium thendigitally sensing the site of the atriocaval junction at the base ofsaid balloon in said right atrium; ligating, intrapericardially, thesuprahepatic inferior vena cava around said shunt at the atriocavaljunction to prevent the reflux of blood from the heart into said retrohepatic vena cava and to fixate said shunt within the venous system sothat the distal portion of said shunt lies within the inferior venacava; inflating the balloon proximal to said renal veins to occlude theflow of blood from said renal veins and said inferior vena cava intosaid retro hepatic vena cava thereby causing blood to be diverted intosaid vena caval opening of said shunt through said shunt and out of saidatrial opening into said right atrium.
 2. A infra diaphragmatic methodof inserting a by pass shunt into the atrio-venous system through theinferior vena cava to ensure a continuous flow of blood through saidatrio-venous system during surgery on the retro hepatic vena cava, theliver and blood vessels by occluding the flow of blood into said retrohepatic vena cava and diverting blood from the renal veins and theinferior vena cava through said by pass shunt into the right atriumcomprising the steps of;providing a closed end flexible by pass shunthaving a pair of openings, one of which is for the right atrium, theatrial opening and the other for the inferior vena cava, the vena cavaopening, said pair of openings are connected to each other by a centralconduit of said shunt so that blood can enter into said shunt throughsaid vena caval opening and exit through said atrial opening andincluding at least two fluid conduit ducts within the wall of said shuntwhich are connected to external ports in the distal end of the shunt forintroducing and withdrawing fluids to at least two expandable andcollapsible balloons which encircle said flexible shunt externally andare connected to said external ports and wherein said shunt issymmetrical on its mid-horizontal axis; performing a venotomy of theinferior vena cava to insert and seat said shunt into a fixed positionwithin the right atrium and within the retrohepatic vena cava; ligating,intrapericardially, the inferior vena cava and positioning said shunt ina fixed position within said right atrium and said retrohepatic venacava so that one of said balloons encircling said shunt rests in saidright atrium and the other is in the inferior vena cava; partiallyinflating said balloon in said right atrium then digitally determiningthe site of the atriocaval junction at the base of said balloon in saidright atrium; ligating, intrapericardially, said suprahepatic inferiorvena cava around said shunt at the atriocaval junction to prevent thereflux of blood from the heart into said retro hepatic vena cava andachieve fixation of said shunt within the venous system anterior to therenal veins; inflating the balloon proximal to said renal veins, thevena cava balloon to occlude the flow of blood from said renal veins andsaid inferior vena cava into said retro hepatic vena cava therebycausing blood to be diverted into said vena caval opening of said shuntthrough said shunt and into said right atrium through said opening insaid right atrium.
 3. The method according to claim 1, further providingthe maximum number of balloons on encircling the external wall of thesaid shunt is four and the maximum number of fluid conduits and externalports for introducing solution into said balloons is four and whereinintroducing and withdrawing fluid is determined in accordance with thenature and position of the injury or the body organ in need of surgicalrepair.
 4. The method according to claim 2, further providing themaximum number of balloons on encircling the external wall of the saidshunt is four and the maximum number of fluid conduits and externalports for introducing solution into said balloons is four and whereinintroducing and withdrawing fluid is determined in accordance with thenature and position of the injury or the body organ in need of surgicalrepair.
 5. The method according to claim 1, further including making anincision in the atrio-caval wall to position the proximal end of saidshunt in the right atrium and to position said distal end of said shuntin said retro hepatic vena cava anterior to said renal veins.
 6. Themethod according to claim 2, further including making and incision inthe atrio-caval wall to position to distal balloon in said right atriumand said proximal balloons in said retrohepatic vena cava anterior tosaid renal veins.